A semiconductor device used for a mobile device represented by a cellular phone is required to suppress a leakage of unnecessary electromagnetic wave toward outside in order to prevent a bad effect on communication properties. A semiconductor package having a shielding function is therefore applied thereto. As the semiconductor package having the shielding function, the one having a structure in which a shielding layer is provided along an outer surface of an encapsulant sealing a semiconductor chip mounted on an interposer board is known.
A semiconductor package using an interposer board in which vias connected to a ground wiring are arranged at an outer peripheral side to suppress the leakage of the unnecessary electromagnetic wave from a side surface of the interposer board outer peripheral side to suppress the leakage of the unnecessary electromagnetic wave from a side surface of the interposer board is known. It is required to enhance electrical and mechanical connection reliability between the shielding layer and the ground wiring of the interposer board in the semiconductor package. Further, it is required to suppress the leakage of the unnecessary electromagnetic wave from the side surface of the interposer board without increasing a size of the semiconductor package.